Hi Karen,
Thanks for reaching out to us! I’d be happy to help you 🙂
The function you used gives you the possibility to add a featured image to posts, pages and events. However, you don’t need to use it, since by default, you can already attach a thumbnail image to any event.
In order to achieve what you want (show thumbnails on a list view), you need to customize the Events Calendar’s template files. Please read our Themer’s Guide for more information about how to do this.
In your case, you’ll probably want to copy the file in /wp-content/plugins/the-events-calendar/src/views/list/single-event.php to /your-theme/tribe-events/list/single-event.php (replace /your-theme with the actual folder name of your theme, of course). Then you can edit that file to display the event’s thumbnail image.
If you’d rather have someone do that tweak for you, we can give you a list of freelancers.
I hope this helps,
Cheers,
Jeremy